title: Impaired fear inhibition learning predicts the persistence of symptoms of posttraumatic stress disorder (PTSD).
abstract: Recent cross-sectional studies have shown that the inability to suppress fear under safe conditions is a key problem in people with posttraumatic stress disorder (PTSD). The current longitudinal study examined whether individual differences in fear inhibition predict the persistence of PTSD symptoms. Approximately 2 months after deployment to Afghanistan, 144 trauma-exposed Dutch soldiers were administered a conditional discrimination task (AX+/BX-). In this paradigm, A, B, and X are neutral stimuli. X combined with A is paired with a shock (AX+ trials); X combined with B is not (BX- trials). Fear inhibition was measured (AB trials). Startle electromyogram responses and shock expectancy ratings were recorded. PTSD symptoms were measured at 2 months and at 9 months after deployment. Results showed that greater startle responses during AB trials in individuals who discriminated between danger (AX+) and safety (BX-) during conditioning, predicted higher PTSD symptoms at 2 months and 9 months post-deployment. The predictive effect at 9 months remained significant after controlling for critical incidents during previous deployments and PTSD symptoms at 2 months. Responses to AX+ or BX- trials, or discrimination learning (AX+ minus BX-) did not predict PTSD symptoms. It is concluded that impaired fear inhibition learning seems to be involved in the persistence of PTSD symptoms.
authors.affiliation: Clinical and Health Psychology, Utrecht University, The Netherlands; Department of Clinical Psychology, VU University Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, The Netherlands. Electronic address: e.m.sijbrandij@vu.nl.
authors.forename: Marit
authors.initials: M
authors.lastname: Sijbrandij
authors.forename: Iris M
authors.initials: IM
authors.lastname: Engelhard
authors.forename: Miriam J J
authors.initials: MJ
authors.lastname: Lommen
authors.forename: Arne
authors.initials: A
authors.lastname: Leer
authors.forename: Johanna M P
authors.initials: JM
authors.lastname: Baas
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D003214:Conditioning, Classical / Q000502:physiology; D005239:Fear / Q000523:psychology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D007859:Learning Disabilities / Q000175:diagnosis / Q000209:etiology*; D008137:Longitudinal Studies; D008297:Male; D008889:Military Personnel; D009426:Netherlands; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D013216:Reflex, Startle / Q000502:physiology; D013313:Stress Disorders, Post-Traumatic / Q000150:complications* / Q000175:diagnosis*; D055815:Young Adult
keywords: Acoustic startle; Classical conditioning; Conditional discrimination; Fear inhibition; Military; Posttraumatic stress disorder (PTSD)